Worked on the rems-project/cn repository to deliver parametrization and substitution support for CN programs, enabling safer type checking and improved reuse of program patterns. The approach involved refactoring core CN program handling and related modules to introduce a parametrized structure, supporting scalable workflows and future extensibility. Implemented the cn_prog_sub_let function to manage substitutions within CN programs, and updated type-checking logic to validate ghost arguments with substituted loads. The work focused on compiler development using ML and functional programming techniques, with particular attention to type systems, resulting in a maintainable codebase that supports more flexible and robust CN program definitions.